Calcining-furnace.



No- 806,894. PATENTED DEC. 12, 1905. G. N.'JEPPSON.

OALGINING FURNACE.

APPLICATION FILED PEB.25, 1903.

3 SHEETS-SHEET 3.

4 UNITED STATES PATENT onrion.

Specification of Letters Patent.

Patented. Dec. 12, 1905.

Application filed February 25, 1903. Serial No. 144,983.

To all whom, it may concern:

Be it known that I, GEORGE N. J EPPSON, a citizen of the United Statesof America, and a resident of the city and county of Worcester,Commonwealth of Massachusetts, have invented certain new and usefulImprovements in Calcining-Furnaces, of which the following is aspecification.

My invention relates to a calcining or roasting furnace in which certainores are subjected to continued high temperature for the purpose ofdriving off the water of combination.

My invention is not confined to any particular kind of ore; but it maybe used with good effect in calcining bauxite. Some bauxite ores containabout thirty per cent. of water of combination, which can only be drivenoff at red heat. Not only is it necessary to subject the ore to a hightemperature, but to continue the heat for a considerable time, for whilethe larger percentage of moisture is driven off in a comparatively shorttime or at a lower heat the last traces disappear only after the ore hasbeen heated to a high heat for a considerable time. It will be noted,therefore, that for economical operation the calcining-furnace must beconstructed to hold the heat and to allow all parts of the mass of oreto be subjected directly to it. Other considerations are freedom fromconstant manip ulation of the ore, continuous operation, ease ofcharging and discharging, avoidance of waste by escape of dust, theprotection of the ore from direct contact with the products ofcombustion, and others which will appear in the description whichfollows.

My invention consists in a furnace the chamber of which contains anumber of refractory tubes open at each end and into which the raw oreis charged and from which it is drawn after calcining. These tubes arepreferably vertical, the ore being charged at the top and discharged atthe bottom by gravity.

The furnace is preferably of the downdraft type, the burning gases beingintroduced near the top of the chamber and the products of combustionbeing carried off in fines at the bottom to a chimney.

The bottom 10 of the chamber A is suitably supported over thedischarging or receiving chamber B. Said bottom consists of the hearthl1 and the perforated floor 12, between which the flues 13 are located.Said hearth is offirebrick supported on cast-iron plates 14, which aremounted on I-beams 15, the ends of which are eYmbedded in and supportedby the walls 16 l The heating-chamber A is formed by the walls 18, 19,20, and 21 and the arched top 22. The inside of the chamber is linedwith firebrick, as shown at 23. The fire-boxes 24 25 are located in endwalls 18 and 19, respectively, and consist of the usual grate 26 26,fire-door 27 27, and ash-pit 28 28. The flues 3O 31 are made between theend walls 18 19 of the chamber and the walls 16 17, extended upward todirect the burning gases upward toward the upper part of the chamber.The chamber contains the vertical refractory tubes 32, which aresupported on the hearth l1 and extend loosely through the collars 33 inthe top 22, allowing the vertical expansion and contraction of saidtubes through the top. These tubes are open at the bottom throughsuitable openings in said hearth and the plates 14 and communicate withthe spouts 34. They may be closed by slidable fire-brick doors, as 35,which are operated in the slides 36 by suitable rods and handles 37. Thetops of said tubes are closed by covers 38. The flues 13 in the bottom10 communicate with the chimney 40 through the flues 13'. v

The operation of the apparatus is as follows: Fires are laid in thefire-boxes 24 25, and the burning gases coming therefrom are directedthrough the flue 31 up into the top of the chamber A. There they beatagainst the tubes 32 on their way downward to the flues 13 13, passingthen to the chimney. By suitable regulation of the size of the openingsto the fines in the floor 12 the heat is held in the chamber until therefractory walls of the firebrick tubes 32 have absorbed it and untilthe heat is practically constant throughout the said chamber. A red heatis thus constantly maintained in the walls of the .tubes. The

ore is then charged into the tops of thetubes,

the high heat of the inside surface of the tubes. No manipulation of theore is necessary, as the heat held by the fire-brick tubes acts directlyon the ore to the center of each tube. The moisture appears to beabsorbed by the highly-heated surface-of the fire-brick, and completecalcination takes place in a comparatively short time. The ore is notsubjected to the direct action of the flame, and thus any impuritiesfrom theproducts of combustion do not become mixed with the ore, andfine ore and dust which might be carried off up the chimney if subjectedto the direct action of the flame are saved. After the calcination iscompleted the gates 35 are drawn and the ore discharged into the chamberB, where it can be taken up as needed. A new charge can then beintroduced as before, and thus the furnace run continuously, or smallcharges can be introduced more frequently and a portion of the contentsof each tube drawn to make the operation more continuous.

My invention is not confined to driving off the water from bauxite orother ores, but may be used for roasting ore to expel arsenic or sulfuror for other purposes for which it is necessary to heat ores.

I claim- 1. A downdraft calcining-furnace comprising a heating-chamber,a fire-box, fiues connecting the fire-box with the upper portion of saidchamber and fiues at the lower portion of said chamber for carrying awaythe products of combustion, a series of tubes within said chamber andextending through the walls thereof, and collars fitted within the Wallsof said chamber and loosely surrounding said tubes whereby the tubes arepermitted to eX- pand longitudinally.

2. A downdraft calcining-furnace commie ing a heating-chamber, afire-box, flues con necting the fire-box with the upper portion of saidchamber and fiues at the lower portion of said chamber for carrying awaythe products of combustion, a perforated fioor interposed between saidheating-chamber and said lower series of flues for retarding the exit ofthe heated gases, a series of tubes within said chamber and extendingthrough the walls thereof, and collars fitted within the walls of saidchamber and loosely surrounding said tubes whereby the tubes arepermitted to expand longitudinally.

3. A downdraft calcining-furnace comprising a heating-chamber, afire-box, fines connecting the fire-box with the upper portion of saidchamber and fines at the lower portion of said chamber for carrying awaythe products of combustion, a perforated fioor interposed between.saidchamber-and said lower series of fiues, a series of fines extendingthrough the walls of said chamber and through the perforated floor andcollars loosely surrounding the said tubes and placed within the wallsof the furnace to allow of longitudinal expansion of said tubes.-

Signed by me at Worcester, Massachusetts, this 21st day of February,1903.

GEORGE N. J EPPSON Witnesses:

ALDUsG. Hreenvs, E. W. DODGE.

